Superheat matching control method for a roll-bond photovoltaic-thermal heat pump system

In this paper, a superheat matching control method (SMCM) for a roll-bond photovoltaic-thermal heat pump (RB-PVT-HP) system is proposed to achieve adaptive control of the target superheat under different operating conditions. The target superheat was determined based on a comprehensive consideration of the stable running superheat and the optimally performing superheat of the system. The effectiveness of the SMCM was experimentally verified. The trigeneration performance tests of the system under the SMCM were conducted in the summer. Results show that the average deviation degrees of superheat were 0.48 °C and 2.09 °C in the heating and cooling processes, respectively. In the heating process, the average input power of the compressor, heating power and coefficient of performance of the system were 5.40 kW, 17.90 kW, and 3.31, respectively, across four days of continuous operation. The average photoelectric conversion efficiency, comprehensive energy output capacity and comprehensive performance of thermal-and-electrical generation were 14.19 %, 21.29 kW and 34.76 %, respectively, during daytime operation. In the cooling process, the average input power of the compressor, cooling power and energy efficiency ratio of the system were 3.82 kW, 7.72 kW, and 2.02, respectively, during nighttime operation.